1. Field of the Invention
The present invention relates to a light projection device and a light guide member used in such a light projection device, and more particularly relates to a light projection device that includes a fluorescent member to which excitation light is applied and a light guide member used in such a light projection device.
2. Description of the Related Art
Conventionally, a light projection device is known that includes a fluorescent member to which excitation light is applied. Such a light projection device is disclosed in, for example, JP-A-2003-295319.
JP-A-2003-295319 described above discloses a light source device (light projection device) that includes: an ultraviolet LD element functioning as a laser light source; a fluorescent material (fluorescent member) which converts laser light (excitation light) emitted from the ultraviolet LD element (LD: laser diode, semiconductor laser) into visible light; and a visible light reflective mirror which reflects visible light emitted from the fluorescent material. In the light source device described above, the visible light reflective mirror which reflects the visible light emitted from the fluorescent material is provided, and thus a predetermined region in the front of the light source device is illuminated.
Incidentally, when the light source device disclosed in JP-A-2003-295319 described above is used as, for example, an automobile headlight, it is necessary to control the light projection pattern of the light emitted from the light source device. Specifically, it is necessary to configure the light source device such that the light projection pattern is horizontally long. Although JP-A-2003-295319 described above does not disclose a light projection pattern, it is expected that the light projection pattern is circular. When the light source device disclosed in JP-A-2003-295319 described above is used as, for example, an automobile low beam (passing headlight), it is necessary to provide a light shielding plate in the light source device and thereby form the light projection pattern into a desired shape. In this case, since part of fluorescent light is shielded by the light shielding plate, the efficiency of utilization of the light is disadvantageously decreased.
In the automobile headlight, it is necessary to switch between a high beam (driving headlight) and a low beam (passing headlight). There is also a headlight that is operated according to steering or the drive of a blinker to illuminate, as with an AFS (adaptive front-lighting system) or a cornering light, an area in a direction in which the automobile turns. Hence, when the light source device disclosed in JP-A-2003-295319 described above is used as the automobile headlight, it is disadvantageously necessary to provide the light source device for each light projection pattern.